Bleeding into renal cysts is a well known and common complication of polycystic kidney disease, but occasionally the cysts can rupture externally, as in this case, into the retroperitoneal spaces.
Retroperitoneal hemorrhage, Radiology Reference Article
Autosomal Dominant Polycystic Kidney Disease (ADPKD) - Genitourinary Disorders - Merck Manuals Professional Edition
007K Polycystic Kidney Disease Cerebral Aneurysm and Cystic Changes in Spermatic cord
Retroperitoneal hemorrhage, Radiology Reference Article
Retroperitoneal hemorrhage, Radiology Reference Article
PDF) Large Retroperitoneal Haemorrhage Following Cyst Rupture in a Patient with Autosomal Dominant Polycystic Kidney Disease
Retroperitoneal hemorrhage due to ruptured renal cyst in PCKD, Radiology Case
007K Polycystic Kidney Disease Cerebral Aneurysm and Cystic Changes in Spermatic cord
Kidneys and Urinary Tract
Autosomal Dominant Polycystic Kidney Disease (ADPKD) Imaging: Practice Essentials, Radiography, Computed Tomography
Renal Cysts - TeachMeSurgery